Shikonin Shields the Heart From Chemotherapy Damage by Restoring Mitochondrial Balance

A chemotherapy drug that has saved countless lives from cancer also carries a hidden cost: progressive damage to the heart muscle that can ultimately lead to heart failure. Doxorubicin, one of the most widely used anthracycline chemotherapeutics, is limited in the clinic precisely because its cumulative cardiotoxicity forces oncologists to cap the total dose a patient can safely receive. Now, a team of researchers in China reports that a natural plant-derived compound called shikonin may offer a way to protect the heart from this collateral damage, by targeting the oxidative stress, mitochondrial dysfunction, cellular senescence, and fibrotic scarring that underlie chronic doxorubicin-induced cardiac injury. The study, published in Molecular Biology Reports, provides both animal and cellular evidence that shikonin treatment can preserve cardiac function in the face of chemotherapy exposure.

The research, led by Guang-qiu Ren and Jing Yang at Puyang Medical College with colleagues from North Henan Medical University and Xinxiang Central Hospital, focused on a compound extracted from the roots of plants in the Boraginaceae family, long used in traditional Chinese medicine. Shikonin is a naphthoquinone, a class of molecules defined by a quinone ring structure that gives them distinctive redox chemistry. Previous work has shown that shikonin possesses antioxidant properties and can protect mitochondria, the energy-producing organelles that are among the first casualties of doxorubicin toxicity. Earlier studies from the same group also found that shikonin alleviates vascular aging in rats fed a high-fat diet by inhibiting oxidative stress and mitochondrial damage, which encouraged the team to test whether similar mechanisms operate in the chemotherapy-injured heart.

To model the clinical problem, the researchers established a chronic doxorubicin-induced cardiotoxicity model in male Sprague-Dawley rats. Doxorubicin was administered to induce the kind of progressive cardiac injury seen in patients undergoing repeated chemotherapy cycles. The animals were then treated with either shikonin or captopril, an established cardiovascular drug used here as a comparator. The team assessed cardiac function using echocardiography, examined myocardial structure and collagen deposition with histological and fluorescence staining, and measured oxidative stress markers, mitochondrial function, and senescence-associated changes through biochemical assays and Western blotting. This multi-pronged approach allowed them to connect whole-organ outcomes, such as pumping performance, with molecular events happening inside individual heart cells.

The results painted a clear picture of what doxorubicin does to the heart over time. Echocardiography revealed impaired cardiac function in the treated rats, while histological analysis showed disruption of myocardial structure and a marked increase in collagen deposition, the hallmark of fibrosis. At the biochemical level, doxorubicin tipped the heart’s redox balance toward oxidative stress, depolarized the mitochondrial membrane potential, and promoted myocardial senescence, the state in which heart muscle cells stop dividing but remain metabolically active and secrete inflammatory and fibrotic signals. Western blotting showed that doxorubicin increased the expression of DRP1 and FIS1, two proteins that drive mitochondrial fission, along with elevated levels of phosphorylated p53 and p21, key components of the senescence signaling pathway.

When shikonin was added to the treatment regimen, these alterations were substantially ameliorated. Cardiac function improved, myocardial structure was better preserved, and collagen accumulation was reduced. The compound restored redox balance, stabilized the mitochondrial membrane, and dampened the senescence program, lowering the expression of DRP1, FIS1, phosphorylated p53, and p21. The comparison with captopril is notable because it situates shikonin’s effects alongside an established cardioprotective agent, suggesting that the natural compound operates in a clinically meaningful therapeutic range rather than producing only marginal biochemical shifts.

To probe the mechanism more directly, the researchers turned to H9c2 cardiomyoblasts, a rat-derived cell line widely used to study cardiac injury in vitro. They performed complementary loss- and gain-of-function experiments targeting DRP1, the dynamin-related protein that orchestrates mitochondrial fission. When the team knocked down DRP1 in doxorubicin-treated cells, the intervention mimicked several of shikonin’s protective effects, supporting the idea that excessive mitochondrial fission is a central driver of chemotherapy-induced cardiac damage. Conversely, when DRP1 was overexpressed, it partially reversed shikonin’s suppression of mitochondrial superoxide accumulation and senescence-associated changes, indicating that DRP1 sits downstream of, or in a feedback loop with, the pathways shikonin modulates.

These findings place mitochondrial dynamics at the center of the doxorubicin cardiotoxicity story. Mitochondria exist in a dynamic equilibrium between fission, which divides damaged organelles for degradation, and fusion, which mixes contents and preserves function. When this balance is disrupted, as happens when DRP1 and FIS1 are upregulated, fragmented mitochondria accumulate, their membranes depolarize, and they leak reactive oxygen species. In cardiomyocytes, which are almost entirely dependent on mitochondrial oxidative phosphorylation and have very limited capacity for self-renewal, this cascade is particularly destructive. The resulting oxidative stress damages proteins, lipids, and mitochondrial DNA, and it activates the p53/p21 axis that pushes cells into senescence.

The senescence component of the study is especially significant for the long-term outlook of cancer survivors. Senescent cells in the heart do not simply sit quietly; they acquire a senescence-associated secretory phenotype, releasing inflammatory cytokines, growth factors, and matrix-remodeling enzymes that promote fibrosis and further dysfunction. By showing that shikonin reduces phosphorylated p53 and p21 expression alongside its mitochondrial effects, the study links two processes, mitochondrial dysregulation and cellular senescence, that are often studied separately but appear to be tightly coupled in the injured myocardium. The fibrotic remodeling that shikonin attenuated in the rat hearts is plausibly a downstream consequence of this senescent, pro-fibrotic signaling environment.

Shikonin itself is an intriguing therapeutic candidate with a growing portfolio of reported actions. Beyond its antioxidant and mitochondrial protective properties highlighted in this study, prior research has documented its ability to attenuate oxidative injury in colon-derived cell lines, activate the Nrf2-ARE antioxidant signaling pathway to protect cochlear neurons from degeneration, and exert antitumor effects against colon cancer. Its pharmacokinetics, toxicology, and pharmaceutical development have been reviewed in recent literature, and the compound has even entered clinical trial discussions. The new study adds cardioprotection during chemotherapy to this list, a use case that would be particularly attractive if shikonin could be co-administered with doxorubicin without interfering with the drug’s anticancer efficacy, a question that remains to be directly tested.

As with any preclinical study, important caveats apply. The work was conducted in rats and in a cardiomyoblast cell line, and the chronic doxorubicin model, while well established, does not capture every dimension of human cardiotoxicity, including the contributions of patient age, comorbidities, and concurrent cancer therapies. The DRP1 overexpression experiments showed only partial reversal of shikonin’s effects, which the authors themselves frame as indicating that DRP1-related mitochondrial dysregulation contributes to, but does not fully account for, the compound’s protection. Human dosing, safety, and drug-interaction studies would be essential before any clinical translation. Nevertheless, the convergence of functional, histological, biochemical, and mechanistic evidence in this study makes a compelling case that shikonin attenuates doxorubicin-induced myocardial injury, senescence, and fibrosis through improved redox and mitochondrial homeostasis, and it identifies the DRP1-driven fission pathway and the p53/p21 senescence axis as promising targets for the next generation of cardioprotective strategies in oncology.

Subject of Research: Shikonin's cardioprotective effects against doxorubicin-induced myocardial senescence and fibrosis via mitochondrial and redox homeostasis

Article Title: Shikonin attenuates doxorubicin-induced myocardial senescence and fibrosis in association with improved redox and mitochondrial homeostasis

Article References: Ren, G.-Q., He, M.-L., Guo, Y.-Q., Li, Z.-X., Liu, H.-J., Li, J., Zhang, J., & Yang, J. (2026). Shikonin attenuates doxorubicin-induced myocardial senescence and fibrosis in association with improved redox and mitochondrial homeostasis. Molecular Biology Reports, 53(1), Article 1649. https://doi.org/10.1007/s11033-026-12790-y

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12790-y

Keywords: shikonin, doxorubicin, cardiotoxicity, mitochondrial dynamics, DRP1, cellular senescence, p53/p21 signaling, myocardial fibrosis, oxidative stress, cardioprotection, naphthoquinone, H9c2 cells